Gº vs T plot in the Ellingham’s diagram slopes downwards for the reaction. (RPMT 2006) (a) Mg⁺ O MgO → (b) 2Ag⁺ O Ag O → (c) C O CO → (d) CO O CO →

In the Ellingham diagram, when the gas is utilized during the reaction, entropy is negative thus the TdS term is positive and thus the upward slope is obtained. However, when carbon and oxygen react to form carbon monoxide, the entropy increases as a gas is formed and thus tends to the positive side resulting the downward slope. Therefore, the correct answer is option (c) 2 1 C⁺ O CO 2 →